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Dynamic recrystallization mechanism, texture evolution development and mechanical characteristics of a Mg–8.7Gd–4.18Y–0.42Zr magnesium alloy by ECAP

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Progress in Natural Science:Materials International 2024年第2期34卷 376-388页

作者： ling Zhang Yinglong li School of Materials Science and Engineering Northeastern University School of Mechanical and Engineering Ningxia Institute of Science and Technology

Equal channel angle pressing is recognized for its ability to refine alloy grains and alter grain orientation, thereby achieve better mechanical performance of the magnesium alloy. This study investigates the microstructures,dynamic recrystallization mechanism, texture development, and mechanical performance of GW94K(Mg–8.7Gd–4.18Y–0.42Zr wt. %) Mg alloy following ECAP-4 passes at 400°C and 3 mm/min. Results show that when high-temperature deformation is undertaken, twin formation is suppressed while dislocation slip is facilitated, increasing dislocation density during deformation. Following ECAP deformation, the sample displayed higher fracture elongation, TYS, and UTS than the as-solutioned GW94K alloy. In particular, the GW94K alloy performed well mechanically after ECAP-4 passes, with an ultimate TYS of 231 MPa, an UTS of 290 MPa, and an elongation of 14.8 %. DDRX and shear bands induce CDRX, both of which are important in plastic deformation. as well as in modifying microstructure and grain orientation during ECAP deformation.

关键词： Dynamic recrystallization mechanism Equal channel angular pressing Magnesium alloy Mechanical performance Mg-Gd-Y-Zr alloy Texture development

Structural engineered living materials

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Nano Research 2024年第2期17卷 715-733页

作者： Yang Geng Zian Jia ling li 635 Prices Fork Road Department of Mechanical EngineeringVirginia Polytechnic Institute and State UniversityBlacksburg VA24061USA

Biological structural materials not only exhibit remarkable mechanical properties but also often embody dynamic characteristics such as environmental responsiveness,autonomy,and self-healing,which are difficult to achieve in conventional engineering *** merging materials science,synthetic biology,and other disciplines,engineered living materials(ELMs)provide a promising solution to combine living organisms with abiotic components,thus facilitating the construction of functional“living”*** natural materials,ELMs possess vitality and hold immense application potential in areas such as medicine,electronics,and construction,captivating increasing research attention *** an emerging branch of ELMs,structural ELMs aim to mimic living biological structural materials by achieving desired mechanical performance while maintaining important“living”*** we summarize the recent progress and provide our perspectives for this emerging research *** first summarize the superiority of structural ELMs by reviewing biological structural materials and biomimetic material design ***,we provide a systematic discussion on the definition and classifications of structural ELMs,their mechanical performance,and physiological ***,we summarize some critical challenges faced by structural ELMs and highlight directions of future *** hope this review article can provide a timely summary of the state of the art and relevant perspectives for future development of structural ELMs.

关键词： structural materials engineered living materials(ELMs) structural ELMs composites mechanical properties

Revealing effect of Al content on oxidation of novel Co-Cr-Nb-W carbide-strengthened superalloy

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Rare Metals 2024年第9期43卷 4521-4534页

作者： Chen ling Shang-Ping li Jie Hou He-li Luo Central Iron&Steel Research Institute Beijing 100081China Beijing GAONA Materials&Technology Co. Ltd.Beijing 100081China

The high-temperature oxidation behavior of novel Co-Cr-Nb-W carbide-strengthened wear-resistance alloys with different Al contents(1wt%,2wt%and 3wt%)at 950,1000 and 1050℃was thoroughly investigated by scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy and field emission electron probe *** porous property of NbC in-situ oxidation products(Nb_(2)O_(5),Co Nb_(2)O_(6)and Co_(4)Nb_(2)O_(9))induces a multi-layered oxide scale with micropores and ***-Cr-Nb-W alloy with 1 wt%Al undergoes catastrophic oxidation and spalling above 1000℃.The outward transportation of Cr and Co is effectively restrained by a continuous Al_(2)O_(3)scale formed around NbC in-situ oxidation region when Al content reaches 3 wt%.The β-Co Al in Co-Cr-Nb-W alloy with 3 wt%Al has an oxidation priority over eutectic carbides and the alloy matrix which are both enriched with Cr,thereby preventing the formation of Cr-depletion area and improving the self-healing ability of the oxide film.A slight change in Al content has a remarkable influence on the cooperative effect of Al and Cr and multiplies the antioxidant capacity of Co-Cr-Nb-W alloy above 1000℃.

关键词： High-temperature oxidation behavior Oxidation kinetics Superalloy Wear-resistant alloy Microstructure

Numerical study on the effective thermal conductivity and thermal tortuosity of porous media with different morphologies

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Science China(Technological Sciences) 2024年第6期67卷 1685-1694页

作者： DU Shen li Dong li Meng-Jie HE Ya-ling Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an710049China

Effective thermal conductivity and thermal tortuosity are crucial parameters for evaluating the effectiveness of heat conduction within porous *** direct pore-scale numerical simulation method is applied to investigate the heat conduction processes inside porous structures with different *** thermal conduction performances of idealized porous structures are directly compared with real foams across a wide range of *** foam structures are reconstructed using X-ray computed tomography and image processing techniques,while Kelvin and Weaire-Phelan structures are generated through periodic unit cell *** detailed temperature fields inside the porous structures are determined by solving the heat conduction equation at the pore *** results present that the equivalent thermal conductivity of Kelvin and Weaire-Phelan structures is similar to and greater than that of the real foam structure with the same strut *** thermal tortuosity of real foam structure is relatively larger and the heat conduction path becomes straighter by adopting the anisotropic *** thermal tortuosity of the fluid channels for Kelvin,Weaire-Phelan,and real foam structures is close to *** thermal conductivity of porous structures with heat transfer fluid increases as the thermal conductivity ratio of fluid to solid becomes larger.A small porosity of porous media leads to a larger equivalent thermal conductivity due to the dominant contribution of porous skeleton in the heat conduction *** derived from parallel and series models,as well as the Maxwell-Eucken models,provide decent predictions of effective thermal conductivity,with an average error of less than 8%in the entire range of thermal conductivity ratio.

关键词： volumetric solar receiver porous morphology direct pore-scale simulation equivalent thermal conductivity thermal tortuosity empirical correlation

Experimental and numerical investigation of two blended blade and endwall configurations

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Chinese Journal of Aeronautics 2024年第9期37卷 150-163页

作者： Tongtong MENG Xin li ling ZHOU Lucheng JI Institute for Aero Engine Tsinghua UniversityBeijing 100084China Schoolof Aerospace Engineering Bejing Institute of TechnologyBeijing 0081China

The Blended Blade and Endwall(BBEW)technique has proven to be effective in control-ling the intersection of boundary layer in corner region of the compressor *** this study,the experiment and analysis of two different BBEW designs are ***,based on a linear cas-cade with 0.7 Mach number inflow,two different configurations,BBEW 1 and BBEW 2,are well ***,according to the experimental result,control effects of these two BBEW configu-rations are validated and compared subsequently under various working *** results demonstrate a reduction in total pressure loss of 12.8%and 29%at the design point for BBEW 1 and BBEW 2,***,the BBEW technique proves effective in suppressing the development of the boundary layer and preventing corner *** by detailed numerical analysis,improvements around the corner region,especially for the boundary layer,are extracted to show the mechanisms and distinctions between the two *** results indicate that BBEW 1 significantly restrains the development of boundary layer before separation occurs,while BBEW 2 directly controls the strength and scale of the corner separation.

关键词： Aerodynamic Computational fluid dynamic Experiment Corner separation Blended Blade and Endwall(BBEW)

Effect of Ellipsoidal Particle Shape on Tribological Properties of Lubricants Containing Nanoparticles

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Chinese Journal of Mechanical Engineering 2024年第4期37卷 231-242页

作者： ling Pan Zhi li Yunhui Chen Guobin lin School of Advanced Manufacturing Fuzhou UniversityQuanzhou 362251FujianChina School of Mechanical Engineering and Automation Fuzhou UniversityFuzhou 350108FujianChina

Adding nanoparticles can significantly improve the tribological properties of ***,there is a lack of understanding regarding the influence of nanoparticle shape on lubrication *** this work,the influence of diamond nanoparticles(DNPs)on the tribological properties of lubricants is investigated through friction ***,the friction characteristics of lubricants regarding ellipsoidal particle shape are investigated using molecular dynamics(MD)*** results show that DNPs can drastically lower the lubricant's friction coefficientμfrom 0.21 to *** shearing process reveals that as the aspect ratio(α)of the nanoparticles approaches 1.0,the friction performance improves,and wear on the wall *** the same time,the shape of the nanoparticles tends to be *** 0.85≤α≤1.0,rolling is ellipsoidal particles'main form of motion,and the friction force changes according to a periodic sinusoidal *** the range of 0.80≤αlipsoidal particles primarily exhibit sliding as the dominant movement ***αdecreases within this range,the friction force progressively *** friction coefficientμcalculated through MD simulation is 0.128,which is consistent with the experimental data.

关键词： Molecular dynamics simulation Nanoparticle additives Ellipsoidal particles Tribological properties

Adaptive Barrier-Lyapunov-Functions Based Control Scheme of Nonlinear Pure-Feedback Systems with Full State Constraints and Asymptotic Tracking Performance

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Journal of Systems Science & Complexity 2024年第3期37卷 965-984页

作者： NIU ben WANG Xiaoan WANG Xiaomei WANG Xinjun li Tao Faculty of Electronic Information and Electrical Engineering Dalian University of TechnologyDalian 116024China School of Information Science and Engineering Shandong Normal UniversityJinan 250014China School of Mathematics Southeast UniversityNanjing 211189China School of Automation Nanjing University of Information Science and TechnologyNanjing 210044China

In this paper,the authors propose an adaptive Barrier-Lyapunov-Functions(BLFs)based control scheme for nonlinear pure-feedback systems with full state *** to the coexist of the non-affine structure and full state constraints,it is very difficult to construct a desired controller for the considered *** to the mean value theorem,the authors transform the pure-feedback system into a system with strict-feedback structure,so that the well-known backstepping method can be ***,in the backstepping design process,the BLFs are employed to avoid the violation of the state constraints,and neural networks(NNs)are directly used to online approximate the unknown packaged nonlinear *** presented controller ensures that all the signals in the closed-loop system are bounded and the tracking error asymptotically converges to ***,it is shown that the constraint requirement on the system will not be violated during the ***,two simulation examples are provided to show the effectiveness of the proposed control scheme.

关键词： Asymptotic tracking control barrier Lyapunov functions full state constraints nonlinear pure-feedback systems

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light(Science & Applications) 2024年第2期13卷 333-346页

作者： Yifan Sun Qian li ling-Jun Kong Xiangdong Zhang Key Laboratory of advanced optoelectronic quantum architecture and measurements of Ministry of Education Beijing Key Laboratory of Nanophotonics&Ultrafine Optoelectronic SystemsSchool of PhysicsBeijing Institute of Technology100081BeijingChina

Compared with electrical neural networks,optical neural networks(ONNs)have the potentials to break the limit of the bandwidth and reduce the consumption of energy,and therefore draw much attention in recent *** far,several types of ONNs have been ***,the current ONNs cannot realize the acceleration as powerful as that indicated by the models like quantum neural *** to construct and realize an ONN with the quantum speedup is a huge ***,we propose theoretically and demonstrate experimentally a new type of optical convolutional neural network by introducing the optical *** is called the correlated optical convolutional neural network(COCNN).We show that the COCNN can exhibit“quantum speedup”in the training *** character is verified from the two *** is the direct illustration of the faster convergence by comparing the loss function curves of the COCNN with that of the traditional convolutional neural network(CNN).Such a result is compatible with the training performance of the recently proposed quantum convolutional neural network(QCNN).The other is the demonstration of the COCNN’s capability to perform the QCNN phase recognition circuit,validating the connection between the COCNN and the ***,we take the COCNN analog to the 3-qubit QCNN phase recognition circuit as an example and perform an experiment to show the soundness and the feasibility of *** results perfectly match the theoretical *** proposal opens up a new avenue for realizing the ONNs with the quantum speedup,which will benefit the information processing in the era of big data.

关键词： process quantum convolution

Application of three-dimensional electron diffraction in structure determination of zeolites

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Chinese Journal of Structural Chemistry 2024年第4期43卷 39-47页

作者： Yuhang li Yang ling Yanhang Ma School of Physical Science and Technology&Shanghai Key Laboratory of High-resolution Electron Microscopy ShanghaiTech UniversityShanghai201210China

Zeolites have received great attention due to their wide applications in various fields such as catalysis,adsorp-tion/separation,ion exchange,*** the atomic crystal structure of zeolites is crucial to understanding their functions and exploring their *** to the difficulty of synthesizing large single crystals,the structures of many zeolites cannot be solved using conventional single-crystal X-ray diffraction(SCXRD)***-dimensional electron diffraction(3D ED)has witnessed rapid development during the past decade and has shown its powerful ability in the structure determination of *** this review,we will briefly introduce the history of 3D ED and summarize recent advances in the application of 3D ED for the analysis of zeolite structures,along with several typical examples in this research field.

关键词： Electron diffraction Three-dimensional electron diffraction Zeolite Structure solution Electron crystallography